Pipe joint gasket

Abstract

A method for assembling a pipe joint including an inner pipe having an outside surface and an outer pipe having an annular groove for receiving a gasket and a pipe joint gasket used in that method. The gasket includes front and back regions, the front region being resilient and relatively rigid, the back region being softer and more resilient than the front region. An interior tip of the back region sealingly engages the inner pipe outside surface and spaces the inner pipe from the front region while the inner pipe is being inserted. The exterior tip of the back region in cooperation with the front and back regions, both secures and seals the front and back regions to the annular groove before inserting the inner pipe. The gasket is displaced by the inserted inner pipe which exerts pressure on both pipes thus sealing the annulus between the pipes. The gasket is further displaced by internal pipe pressure or external pressure which exerts proportionally greater sealing force on both pipes.

I claim: 
     
       1. A method for assembling a pipe joint wherein the pipe joint includes an inner pipe having an outside surface and an outer pipe having an annular groove for receiving a gasket, comprising the steps of: providing a gasket, which gasket includes front and back regions, the front region being resilient and relatively rigid, the back region being softer and more resilient than the front region, a joint sealing means for sealingly engaging a portion of the back region with the inner pipe outside surface and for spacing the inner pipe from the front region while inserting the inner pipe, pipe engaging means, which means cooperates with the front and back regions, for both securing and sealing said front and back regions before inserting the inner pipe, wherein the gasket is defined by exterior and interior contours, the exterior contour being proximate the annular groove and the interior contour being proximate the inner pipe outside surface and where the exterior contour closely resembles the shape of the annular groove, but has less curvature than the annular groove in the gasket back region;   bending the gasket;   setting the gasket into the annular groove;   securing and sealing the gasket front and back regions in the annular groove so the gasket exterior surfaces of the front and back regions are placed in intimate contact with the annular groove to prevent foreign materials from being trapped between the gasket exterior surfaces and the annular groove and to prevent dislodgment of the gasket during assembly;   inserting the inner pipe into an aperture defined by the interior contour;   preventing the inner pipe from contacting the front region during insertion;   requiring less force to insert in the inner pipe into the outer pipe; and   displacing the gasket in the annular groove during said step of inserting so the back region is displaced radially outward.   
     
     
       2. A pipe joint gasket to seal the open area between an inner pipe having an outside surface inserted into an outer pipe having an annular groove for receiving the gasket, comprising: a front region being resilient and relatively rigid;   a back region being softer and more resilient than the front region;   wherein said front and back regions each have an exterior surface proximate the annular groove and an interior surface proximate the inner pipe outside surface when the inner pipe is inserted into the outer pipe, the exterior and interior surfaces of said front and back regions defining distinct exterior and interior contours;   wherein the exterior contour closely resembles the shape of the annular groove, but has less curvature than the annular groove in said back region;   pipe engaging means, which means cooperates with said front and back regions, for both securing and sealing said front and back regions to the annular groove before inserting the inner pipe so the exterior surface of the front and back regions are placed in intimate contact with the annular groove and so foreign material is not trapped between the exterior surfaces and the annular groove; and   joint sealing means for sealingly engaging a portion of said back region with the inner pipe outside surface and for spacing the inner pipe from said front region while the inner pipe is being inserted into the outer pipe.   
     
     
       3. The gasket of claim 2, wherein said pipe engaging means includes means for bending said back region prior to placing the gasket into the annular groove. 
     
     
       4. The gasket as set forth in claim 3 wherein imperfections on the inner surface of the outer pipe and the outside surface of the inner pipe are isolated and sealed by the gasket. 
     
     
       5. The gasket as set forth in claim 3 wherein the interior contour further defines an aperture having a varying diameter and the smallest diameter being in said back region. 
     
     
       6. The gasket of claim 5, wherein said joint sealing means includes means for receiving the inner pipe in an aperture defined by the interior contour of the back region. 
     
     
       7. The gasket as set forth in claim 6 further including means for displacing said back region radially outward during the insertion of the inner pipe. 
     
     
       8. The gasket of claim 7 further including means, responsive to internal pipe pressure, for both urging a portion of the front region interior surface to sealingly engage the inner pipe outside surface and for increasing sealing forces between the exterior surfaces and the annular groove and between the inner pipe and said joint sealing means. 
     
     
       9. The gasket of claim 8 further including means, responsive to external pressure, for increasing the sealing forces between the exterior surfaces and the annular groove and between the inner pipe and said joint sealing means, wherein pressure is exerted on the inner and outer pipes so as to constitute a sealing area in the form of a converging wedge focused against said back region. 
     
     
       10. The gasket as set forth in claim 9 further comprising means for responding to external forces by exerting additional pressure on the inner and outer pipes proportional to the external forces. 
     
     
       11. The gasket as set forth in claim 2, wherein said front region is sufficiently rigid to keep the gasket within the annular groove. 
     
     
       12. The gasket as set forth in claim 11, wherein the rigidity of said front region is between 75-95 Shore A durometer. 
     
     
       13. The gasket as set forth in claim 12, wherein said back region is sufficiently soft to allow easy insertion of the inner pipe into the outer pipe. 
     
     
       14. The gasket as set forth in claim 13, wherein the rigidity of said back region is between 40-65 Shore A durometer. 
     
     
       15. The gasket as set forth in claim 14, wherein the gasket is constructed from commercially available elastomers or plastics.